1. Field of the Invention
This invention relates to a support device for a motor in which it is possible to improve the accuracy of rotation of the motor used in the image forming apparatus such as a copying machine, printer, etc.
2. Description of the Related Art
In the image forming apparatus, printer, etc., a paper or resin sheet is conveyed by a transport belt to the image forming station where an image is formed on the transported paper or resin sheet. If this transportation is not stable, deformation of the shape, an unevenness of density, etc. in the image are caused to occur, extremely deteriorating the quality of the image. Over the years, therefore, stabilizing the transportation has been a necessary and indispensable subject.
To this purpose, it is first necessary to enhance the accuracy of rotational movement provided by the motor.
So, as far as the machine that necessitates a highly accurate rotation is concerned, it has been common practice in the art that an output shaft of the motor and a driven shaft of the machine are connected directly to each other without any intermediary such as a gear train or endless belt, that is, the direct drive type of motor (hereinafter called the "DD" motor) is employed, which is free from the deterioration of the accuracy of rotation owing to the gear train or endless belt. In the case of using the DD motor, however, the eccentricity in the connection between the output shaft of the motor and the driven shaft of the machine which would have no influence when the driving torque transmission is in the form of the gear train or endless belt has a very large influence on the accuracy of rotation. At the same time, the presence of this eccentricity becomes a cause of deforming the motor and its carrier.
For this reason, in the prior art, to eliminate the above-described drawback, a method has been employed that when installing the motor on the machine, a rubber material or the like is sandwiched between the motor and the machine so that the eccentricity of the shafts is absorbed by the deformation of the rubber material.
With the DD motor now generally used, however, the eccentricities in its output shaft cannot be avoided. So, in many cases, even if it is mounted on the machine through the rubber material or the like, the bad influence of the eccentricity cannot be sufficiently removed.